Ultrawide angle and high resolution projection objective



350-463 SR olv Jan. 30, 1968 N. RICKLESS 3,366,435

- ULTRAWIDE ANGLE AND HIGH RESOLUTION PROJECTION OBJECTIVE Filed Aug.17, 1964 I.\'\'F\'T( )R NATHAN RICKLE S S BY%CJQWAV United States PatentOffice 3,366,436 ULTRAWIDE ANGLE AND IllGH RESOLUTION PROJECTIONOBJECTIVE Nathan Rleldess, Brighton, N.Y., asslgnor to Bauseh It LombIncorporated, Rochester, N.Y., a corporation of New York Filed Aug. 17,1964, Ser. No. 390,005

- 4 Claims. (Cl. 350l76) ABSTRACT OF THE DISCLOSURE An ultrawide angleprojection objective of at least 153 image field angle for imaging aflat object surface onto The present invention relates to a projectionobjective of the ultrawide angle type and more particularly it relatesto improvements in such objectives which project an image of a flatobject onto a sphericaly curved screen.

In designing an ultrawidc-field projection objective which forms acurved image of matching quality onto a curved screen, the problem isgenerally centered around efforts to match the curvature of the field atevery angular position thereof to a specific curvature of screen.Although this problem in itself is relatively complexvand formidable,other problems confront a lens designer of projection lenses when highintensity lamps such as the mercury zenon lamp is used in projectors ofmodern design. Such.

a high temperature lamp may actually soften glass lenses located nearthe diaphragm position and therefore care must be used in the lensdesign to provide proper lens .materials as well as sufiicientventilation spaces for coolmg an.

Considering the above mentioned difficulties, it is an object of thepresent invention to provide a novel ultrawide-angle projectionobjective having excellent correction of the usual image aberrationssuch as spherical and chromatic aberrations, coma, distortion andastigmatic conditions.

It is a further object to provide such a device which forms aspherically curved image of a fiat object surface, the image shape beingdesigned to match a specified curvature of screen on which the image isprojected.

It is a further object to provide such a device which is especiallyadapted for use in projectors having very high temperature lamps, theadvantageous structures being found in the lens materials and provisionsfor ventilation of the hottest parts of the objective.

Further objects and advantages will be apparent from a study of thefollowing specification taken together with the accompanying drawingwherein the single figure is an optical diagram representing a preferredform of the present invention.

The projection objective as illustrated in the drawing is preferablypositioned horizontally and is generally designated by the numeral 10.In the present invention an objective lens has been produced whichprojects an image of a flat film or diapositive 11 onto a sphericalycurved screen 12 having a prescribed curvature, the field formed3,366,436 Patented Jan. 30, 1868 2 by said lens having a shape whichclosely conforms to the screen 12.

According to the present invention, said objective 10 includes apositive group of lenses on the short or front conjugate side which areseparated by a diaphragm 13 from a negative group of lenses which lie onthe long conjugate side, the lenses in each group being so constructedand arranged with respect to each other that all of the usual chromaticas well as monochromatic aberrations are corrected in an excellentmanner as mentioned heretofore. Said front conjugate has a numericalvalue which is substantially 56% of the equivalent focal lengthof theobjective.

The front lens group on the object or short conjugate side of objective10 comprises a positive doublet lens member which is composed of a frontnegative meniscus lcns designated l lying in edge contact with a doubleconvex positive lens designated II, the adjacent lens surfaces beingsuch as to allow an axial airspace therebetween.

Lens 1 is spaced at an axial distance which is represented by Srearwardly of the object plane ll and at an axial distance representedby S: from lens ll.

Spaced rearwardly at a distance S, from lens I! is a series of threemeniscus lenses which are concave toward the diaphragm 13, the first ofwhich is positive in power I and is designated lll. Following lens litwith an intervening airspace S, thcrebctwcen is the second lens of thegroup, and it is designated IV and is negative in focal length. e

As aforesaid, the objective I. is designed as a part of a projectorusing a high intensity light source such as a mercury-zenon lamp whichresults in highly localized intense heat zone adjacent to the diaphragm13. In fact the heat is of such a high order as to soften the knownglasses which are available for lens manufacture. Because of this factthe third lens in said series, designated V, is made of fused quartz,lens V being spaced at an axial distance S from lens IV and thediaphragm 13 being spaced rcarwardly at a distance S, from lens V.

With regard to the rearward group of negative lens members which aredesignated successively VI and VII, both of these members Since bothlens members are formed of the usual optical glass, lens Vl must bespaced at a safe distance designated 8, rearwardly of the vertex of lensV, the extra large distance serving to facilitate forced ventilation inthat zone.

Spaced rearwardly of lens V] at an axial distance desig nated S; is thelens Vll, the dispersive lenses VI and VII together providing a fieldangle of at least 153 for a spherically curved field 12 or image havingexcellent resolution. The lenses I to Vll are optically aligned on anaxis 14 and distortion of opposing corrective sign and value ispurposely incorporated in the lens members to properly balancedistortion in the final image.

The construction data for the objective 10 is given in the table ofmathematical statements herebelow, the values thereof being given forthe focal lengths --F F F -F F -F and F relating respectively to thelenses 1 to VII, and the minus sign used therewith denotes negativefocal lengths; the value also being given for the radii which are s- 1 sm R10- cessive lens surfaces, the minus sign meaning that the surface isconcave toward entrant light, the lens thicknesses of the successivelenses 1 to VII being designated r, to 1-,, and the successive axialairspaces S, to S. being as specified heretofore, and F designating the?equivalent focal length of the objective 1..

are negative meniscus in form.-

" ib n, -41 -R of the suc- 4 Absolute values:

Absolute values: 2.6$F F 3.23F l.lF R l.344F n (I)=l.805 7(|)=25.4 2.73FF 3.33F l.683F -R 2.057F n (lI)=l.Sl7 7(II)==64.5 23.49F -F 28.7lF.50300F S; .6l500F n flll) =1 1.5 [7 III) =64.S l.26F F l.54F .02l4lF S;.026l5F 5 n (IV)-=l.62l 7(lV) 36.2 l.452F F l.774F .92000F S, l.l2000F n(V)-= l .45 8 (V) =67 .6 7.t7F --F 8.7$F .086l0F S .l05l0F n (V[)=1.5171(Vl)=64.5 l.9l2F R; 2.336F .00465F S, .00569F n (;Vl'l)=l.Sl7(V1I)==64.5 l.478F R, l.806F .0l920F S .02340F l.537F R; l.879F .70100FS, .85600F 10 In objective 10, the diameter of the aperture in the1o.42o1= n-. 12.72o1= .767ooF s, .937o0F diaphragm 13 is substantially2R .589F R .7l9F .l537OF t .18790F In the chart below the numericalvalues for all of the .867F R. l.059F 53700F r, 65500F constructionaldata related to one preferred form of the .566F R .692F 19210F 1,,23470F objective 10 are given, the symbolism having the same .508F R.620F ,10330F t ,1Z630F 15 meaning as heretofore, the scalar dimensionsbeing given ,439F R, .53$F 09570F 11690F in millimeters, and E.F.L. andF.F.L. meaning respec l.680F R 2.052F .1S370F t .l8790F tivelyequivalent focal length and front conjugate of the .407F -R .497F.23920F t-; .29240F objective, considering the objective as a projectionlens.

' E.F.L.=t4.505 F.r.n.=2t.sss rm. Augle=153 Lens Focal Length RhdflThickness Spaces m, w

s, =24.868 R1 94.824 1.. -r| -=474.a4 n=mo 1. 805 25.4

R =7a.m

swims Ba 75.868 F1! -i2s.ss2 t:=28.50 1.511 64.5

-11: =a1s2ao s,=4s.400 RI 29.107 Fm =1as1a0 ti=9.50 1.517 64.5

RI =42ss5 S|= 4250 R1 I231) IV -Frv -uo1.o n nn 1.021 36.2

Re ==Z6JI9 Ba -0.230

RI 112L677 V Fv 62.488 i|=4.73 1.4584 67.0

Rit 83.176

Su=0.l)50

81=34J50 Ru' 20.137 VI 4 =11.s17 n=1.sc 1.511 64.5

St==37550 -R =l54.450 v11..... -1rm=3s4.7s t1=ll.83 1.517 64.5

Ru=83.l76

The refractive index u and Abbe number 7 relating Although only-a singlespecific example of the present to the successive lenses I to VII haveabsolute values as 45 invention has been shown and described in detail,other given in the table of mathematical statements herebelow, forms arepossible and changes and substitutions may be Absolute values: Absolutevalues: made in specific values within the stated ranges without L800HMD 10810 20 0 7(I) 3O.o departing from the spirit of the invention asdefined in 1. An ultra wide angle projection objective which 1 456 nn(v)1 460 62 0 ,Y(v) 72 forms a high resolution curved image of a flatobject L51O HDWD L53O 60.0 Y(vn 7o.o !surface, the projection angle forthe objective being at 60. V11 10. east lsw nngvln l s30 o fl o 5 thefront conjugatebeing substantially 56% of the More specifically theconstructional data for one sucequivalent fgcal length of the objective,

i form of the N 'Y said objective comprising a front collective lensgroup mathemaucal staumfnts herebilow which is airspaced from a reardispersive less group wherem the symbolism has the same meaning asexplained and i d d a diaphragm therebetween,

60 said front collective group comprising a foremost R,=2.l24FS,=.02378F negative meniscus lens designated I which is spaced R=L642FS,=l.0200F at an axial distance S, away from said object sur- R;=1.708FS =.0956F face, said lens being concave toward said diaphragm, R=ll.570F S =.00517F a double convex lens lying in edge contact with lensR =.654F S,=.02l3F 5 I and having a meniscus shaped airspace S, there- R=.963F S-,=.7780F between, said convex lens being designated II, R=.629F S.=.8520F a series of three convex-concave lenses which are con-R,=.564F t =.1708F cave toward said diaphragm and are respectivelyR,=.487F t,=.5960F designated III, IV and V, said lenses being spaced R=1.866F t,=.2134F -7 from lens II and from each other by axial spaces -R=.452F t =.ll48F which are successively designated 8,, S and S the R=l.ll7F t ==.l063F space between vertex of lens V and said diaphragm -R=l.222F I =J708F being designated S -R =l.870F t =.2658F said reardispersive lens group comprising a pair of S =.5590F 7 negative meniscuslenses which are designated VI and VII in order from the diaphragm, thesuccessive interlens axial airspaces from lens V to lens VI and fromlens VI to lens VII being designated S and S; respectively,

the individual focal lengths of lenses I to VII being designatedsuccessively F F F -F F F F wherein the minus sign designates negativefocal lengths,

the specific values for said focal lengths, airspaces, and lensthicknesses in terms of F which represents the equivalent focal lengthof siad objective being substantially as specified in the table givenherebelow.

2. An ultrawide angle projection objectie which forms a high resolutioncurved image fa fiat object surface,

the projection angle for the objective being at least 150",

the front conjugate being substantially 56% of the equivalent focallength of the objective,

said objective comprising a front collective lens group which isairspaced from a rear dispersive lens group and includes a diaphragmtherebetween,

said front collective group comprising a foremost negative meniscus lensdesignated I which is spaced at an axial distance 8, away from saidobject surface, said lens being concave toward said diaphragm,

a double convex lens lying in edge contact with lens I and having ameniscus shaped airspace S therebetween, said convex lens beingdesignated II,

a series of three convex-concavo lenses which are concave toward saiddiaphragm and are respectively designated III, IV and V, said lensesbeing spaced from lens 11 and front each other by axial spaces which aresuccessively designated 8;, S, and S the space between vertex of lens Vand said diaphragm being designated Sgsaid rear dispersive lens groupcomprising a pair of negative meniscus lenses which are designated. VIand VII in order from the diaphragm, the successive interlens axialairspaces from lens V to lens VI and from lens VI to lens VII beingdesignated S and S respectively,

the individual radii of the successive lens surfaces of lenses I to VIIbeing designated respectively R; to R and having values as given in thetable of mathematical statements herebelow, the minus sign 'usedtherewith denoting a lens surface which is concave toward entrant light,the successive airspaces S to S and successive lens thicknesses r; to r,of said lenseshaving values as given in said table,

the specific values being given substantially in terms of F whichrepresents the equivalent focal length of said objective,

3. An ultra wide angle projection objective which forms a highresulution curved image of a flat object surface, the projection anglefor the objective being at least lSO",

the front conjugate being substantially 56% of'thc equivalent focallength of the objective,

said objective comprising a front collective lens group which isairspaced from a rear dispersive lens group and includes a diaphragmtherebetween,

said front collective group comprising a foremost negative meniscus lensdesignated I which is spaced at an axial distance S; away from saidobject surface, said lens being concave toward said diaphragm,

a double convex lens lying in edge contact with lens I and having ameniscus shaped airspace 8, therebctween, said convex lens beingdesignated II,

a series of three convex-concave lenses which are concave toward saiddiaphragm and are respectively designated III, IV and V, said lensesbeing spaced from lens II and from each other by axial spaces which aresuccessively designated S S and S the space between vertex of lens V andsaid diaphragm being designated 8;,

said rear dispersive lens group comprising a pair of negative meniscuslenses which are designated VI and VII in order from the diaphragm, thesuccessive interlens axial airspaces from lens V to lens VI and fromlens VI to lens VII being designated S and 8 respectively,

the individual radii of the successive lens surfaces of lenses I to VIIbeing designated respectively R to R and having values as given in thetable of mathematical statements herebelow, the minus sign usedtherewith denoting a lens surface which is concave toward entrant light,the successive airspaces S to S and successive lens thicknesses t; to tof said lenses having values as given in said table,

the specific values being given substantially in terms of P whichrepresents the equivalent focal length of said objective,

the refractive index n and the Abbe number I of the glasses in saidlenses I to VII having values substantially as given in the tableherebelow,

the diameter of the aperture in said diaphragm being 7 4. An ultra wideangle projection objective which forms a high projection angle for theobjective being at surface, the projection angle for the objective beingat least 150,

8 from lens VI to lens VII being designated S and 8 respectively, theindividual focal lengths of lenses I to VII being designatedsuccessively -F F F -F F the front conjugate being substantially 56% ofthe 5 --F 1, -F wherein the minus sign desigequivalent focal length ofthe objective natcs negative focal lengths,

said objective comprising a front collective lens group the successivelens radii numbering from the object which is airspaced from a reardispersive lens group side being designated R, to R and the minus v(--)and includes a diaphragm therehctween, sign used therewith denotingthose lens surfaces said front collective group comprising a foremostwhich are concave toward entrant light, the symbos negative meniscuslens designated I which is spaced u and v designating respectively therefractive inat an axial distance 5; away from said object surdex andAbbe number of the optical materials from face, said lens being concavetoward said diaphragm, which the lenses are made,

a double convex lens lying in edge contact with lens the numericalvalues of the constructional data for I and having a meniscus shapedairspace S; there- 15 one form of said objective being given inmillimeters between, said convex lens being designated II, in the chartherebelow,

E.F.L.=-l4.505 realiz s-56s Pro}. An 1e=153 Lens Focal Length RsdttThickness Spaces m; r

B; =24.86S at 04.624 I. -Fi -m.34 n==7.eo L805 25.4

mt =7au4 s -1.030 Rt :mtas r1. 1' =r2esa2 r|=2a.5o mm 04.5

-m =a1azao 81=45A00 n, =29J07 Fm -1s5.130 n=a50 1.517 eta a. ==-t2.sss

S|=4.25(l R1 IV -Frv -11e1.o ti=5.tt 1. 621 315.2

Rs =25.1l9

spew B; ere" v.... Fv -62.438 4.73 1.4524 67.8

m ssive B7=3tl.550 -Ru=2lll37 VI "FYI =1!.s17 t.=7.50 1.517 cs5-Ru=4ll65tl swsmsro "Rr1=54.4w v1I-.-. -Fvu=354.76 t1=n.s3 1.511 54.5

-R ==83.t7B

a series of three convex-concave lenses which are conwherein E.F.ldenotes the equivalent focal length, e lowflfd Said dlaphfagm and are 'fp y and F.F.L. denotes the front conjugate, considering designated III,IV and V, said lenses being sp that entrant light is first directed fromthe transparent from lens II and from each other 'by axial spaces m 0 edrough lensL which are successively designated 8;, S and S the spacebetween vertex of lens V and said diaphragm No refgrences citci beingdesignated S said rear dispersive lens group comprising a pair ofnegative meniscus lenses which are designated VI and VII in order fromthe diaphragm, the successive interlens axial airspaees from lens V tolens VI and DAVID H. RUBIN, Primary Examiner.

JOHN K. CORBIN, Examiner.

